The present invention relates to chemical mechanical planarization (“CMP”) polishing compositions (CMP slurries, CMP composition or CMP formulations are used interchangeably) in the production of a semiconductor device, and polishing methods for carrying out chemical mechanical planarization. In particular, it relates to polishing compositions comprising composite abrasive particles that are suitably used for polishing patterned semiconductor wafers that composed of Cobalt (Co), SiN and oxide materials.
There are several CMP steps in integrated circuit (IC) manufacturing process, such as bulk metal layer, traditional Cu barrier layer polishing, most recently Co barrier layer polishing, shallow trench isolation (STI), inter-layer dielectric (ILD) CMP and gate poly CMP etc.
Typical polishing compositions for such applications contain: abrasive, corrosion inhibitor, and optionally other chemicals. Other chemicals could be included in barrier CMP polishing compositions to improve stability, booster removal rate, suppress removal rates, or inhibitors to provide metal film surface from corrosion during and post-CMP process.
Among common abrasives used in CMP slurries, such as silica, alumina, zirconia, titania and so on, ceria is known for its high reactivity toward silica oxide and is widely used in STI CMP composition for the highest oxide removal rate (RR) due to the high reactivity of ceria to silicon oxide. However ceria particles are also known to cause severe scratching, which would be even more problematic for polishing metallic films. Ceria particles are not typically used as abrasives for barrier CMP slurry compositions and with soft polish pad. So there is need to develop compositions on novel abrasive types for advanced applications.
As the semiconductor technology has advanced, there have been a lot of new challenges with the use of new film materials and complex integration schemes. For example, cobalt has been introduced as a both a barrier material for copper structure as well as an interconnect line material. There are a number of integration schemes in works that require varying selectivity between cobalt and other types of films. Certain applications require 1:1 polishing selectivity between Co and oxide dielectrics, some other applications may require additional polish stops on different films such as tungsten, amorphous silicon, polysilicon or low-K films. Certain applications may also require high removal rates of some underlying films such as titanium nitride or titanium. These challenging integration schemes requires novel slurry compositions to meet the CMP performance targets.